Sun bathers beware. New test results from Consumer Reports found not all sunscreens block UV rays as advertised.

"Out of the 58 sunscreens that we tested this year, 20 of them did not meet the SPF listed on the label," Consumer Reports' Trisha Calvo told NBC News.

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Five products with an SPF label of 50 were found to have an actual SPF between zero and nine.

The Personal Care Products Council, which represents the sunscreen industry, disagreed with the findings and wrote in a statement:

"It appears that Consumer Reports' testing methods are not consistent with those used by FDA, and therefore are not the same testing as required by the product manufacturers to assign the SPF designation."

Consumer Reports recommends choosing a sunscreen with at least an SPF of 40, which should increase your chances of having an actual sun protection factor of 30.

Consumer Reports' top 3 sunscreen picks are:

Coppertone Sport High Performance SPF 50

Neutrogena Ultra Sheer SPF 45

Generic brands at Walmart, Target and Walgreens

The organization also suggests steering clear of so-called "natural" sunblocks.

"Natural sunscreens tend not to perform as well as ones with active chemical ingredients, such as avobenzone," Calvo said.